Weighted average in a report

[cdipaolo]

Hi, I'm new to Access so forgive me if there is an obvious answer. The description below isn't the actual fields but it makes it easier to understand.

I have a report that lists total sales by location and customer satisfaction by location). I would like to show a weighted average of customer satisfaction at the bottom of the report. I know how to sum the total volume to figure out what % of volume each location has. I can also get the contribution to the total weighted average for each by multiplying customer satisfaction for that location * (location volume/total volume). However, when I try to add all of those individual weightings up at the bottom I'm trying to sum up individual fields that uses an overall sum, so it's giving me an error.

Any advice is greatly appreciated.

Thanks

Chris